The tomato is one of the most widely grown and valuable fruit crops world-wide. Despite its popularity and important contribution to human nutrition, the commercially produced fruit is widely viewed as having poor taste and its flavor is a major source of consumer dissatisfaction. Flavor is a complex trait that appears to be driven by the combination of flavor compounds, including certain volatile compounds.
Tomato breeding programs have focused mainly on resistance to biotic and abiotic stress, improved yield, storage quality, and color (Bai and Lindhout 2007). Improving tomato flavor through breeding has proven to be a much more daunting task; flavor is a complex trait that is comprised of a mixture of sugars, acids, and about 30 different volatiles (Baldwin et al 2008; Tieman et al 2006; Klee, 2010). Each volatile has its own biosynthetic pathway, and precursors include amino acids, fatty acids, and carotenoids (Goff and Klee 2006).
Guaiacol (2-methoxyphenol), a volatile compound described as having a smoky or medicinal aroma (Alvarez-Rodriguez et al. 2003), is found in many processed food products such as wine, roasted coffee, tea, cocoa, and food additives like liquid smoke (Bonvehi and Coll 1998; Dorfner et al 2003; Guillen et al. 1995; Hayasaka et al 2010; Kumazawa and Masuda 2002). Guaiacol is not commonly found in fresh fruits and vegetables, but is an important contributor to tomato flavor. Since guaiacol has been described as an undesirable compound in many fruits, based on its medicinal-like aroma (Zierler et al., 2004; Zanor et al., 2009), identifying genes responsible for its synthesis could prove useful in breeding programs focusing on altering tomato flavor.